Discrepant events and Demonstrations
B. Law
Unionville High School
benjamin.law@yrdsb.edu.on.ca
Demonstration is a scientific
experiment carried out for the
purposes of demonstrating scientific
principles.
Students may have learned about
the scientific principles before
seeing the demonstration.
Discrepant event is one that does
not appear to follow basic “rules of
nature”.
Outcome of a discrepant event is
unexpected or contrary to what one
would have predicted.
There is no guarantee of learning when
students observe or experience discrepant
events. (They may have ignored or rejected
it)
Some strategies are recommended:
1. predict the outcome;
2. construct one or more theoretical explanations;
3. observe the outcome;
4. modify the theoretical explanation;
5. evaluate competing explanations;
Safety comes first in both
discrepant event or
demonstration
(A-1) Singing plastic tubes
Material: plastic vacuum tube / tubes from dollar
store
[Related to: Gr. 11 physics – sound unit]
High pitch sound is produced when swirling a long
plastic tube
(A-2) Blue Bottle demonstration - The solution will turn blue when you
shake it. It will turn back to colorless after a short while
Materials: Dextrose, Potassium Hydroxide, methelene blue
indicator
[Related to: Gr. 9/10 Science – Chemistry unit]
Explanation:
http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/BOTL/PAGE1.HTM
(A-3) Needle-proof balloon – A normal party balloon will
not pop even a sharp needle is inserted into it.
Materials: Syringe/needle , balloons
[Related to: Gr. 9/10 Science – Chemistry unit]
(A-4) Fireproof balloon – A normal party balloon will not pop
when it is placed above a burning candle.
Materials: Candle, Balloon (with water inside), retort stand and
ring clamp.
[Related to: Gr. 9/10 Science – Chemistry unit]
(A-5) Colorful fireball – Fireballs in different colors
will be produced when spraying the solution on a
burning candle.
Materials: Spray bottles, Solution contains mineral
nitrates and alcohol
[Related to: Gr. 9/10 Science – Chemistry unit]
(A-6) Isopropanol / Ethanol in pop bottle – vigorous
combustion reaction can be observed
Materials: Isopropanol / Ethanol, dry 2L pop bottles,
candle
[Related to: Gr. 9/10 Science – Chemistry unit]
(A-7) Isopropanol / Ethanol in big water bottle -vigorous combustion reaction can be observed
Materials: Isopropanol / Ethanol, Empty distilled water
bottle (large size)
[Related to: Gr. 9/10 Science – Chemistry unit]
(A-8) Is it illegal to burn this paper bill? – Paper bill
can not be burnt when it is soaked with 50/50 rubbing
alcohol.
Materials: Isopropanol, $5 paper bill, candle
[Related to: Gr. 9/10 Science – Chemistry unit]
(A-9) Water “fall” ? – Good way to demonstrate
the force between water molecules (surface
tension) in particle theory.
Materials: Erlenmeyer flask , wire mesh, water
[Related to: Gr. 9 Science – Chemistry unit]
(A-10) CCD – Infra-red detector – IR beam can be detected
by using a digital camera/video camera. Make the invisible
become visible.
Materials: Any remote control, Video camera / Digital
camera ,TV/ LCD projector with video input
[Related to: Gr. 11 Physics – Optics unit]
(A-11) Antigravity coffee can
Materials: Large Coffee can, 1 kg mass, duct tape
[Related to: Gr. 12 Physics – Energy unit]
(B-1) Hammering a nail into a wood over head (Newton’s
1st law)
Materials: Few text books, block of wood, nail and
hammer.
[Related to: Gr. 11 Physics – Dynamics unit]
(B-2) Hydrogen Rocket – Newton’s 3rd Law
Materials: Empty Pringles’ can, Sulfuric acid, Zinc metal, Candle.
[Related to: Gr. 11 Physics – Dynamics unit]
(B-3) Few Bernoulli’s principle demonstrations (escaping egg,
jumping coins, suspending ping pong ball, suspending squash
ball)
Materials: raw eggs, small paper cups, coins, 250ml beaker,
ping-pong balls, squash balls, hair dryer and leave blower.
[Related to: Gr. 12 Physics – Dynamics unit]
(B-4) Centripetal force demonstration
Materials: Wooden stage with strings attached to it, bucket with
water
[Related to: Gr. 12 Physics – Dynamics unit]
(C-1) That’s a cool pen holder
Materials: Erlenmeyer flask, party balloon, electric kettle, beaker
with cold water
[Related to: Gr. 9/10 Science – Chemistry unit]
(C-2) Sacrificing Gummy Bear
Materials: Sodium Chlorate (KClO3), large clean Pyrex test tube,
retort stand and test tube clamp, one gummy bear, Bunsen
burner.
[Related to: Gr. 9/10 Science – Chemistry unit, Gr. 11/12 Physics
– Energy unit]
Explanation: http://www.woodrow.org/teachers/chemistry/institutes/1988/gummybear.htm
(C-3) Density demonstration – suspending soap bubbles in a
fish tank
Materials: Empty fish tank, baking soda, a bottle of vinegar,
soap bubbles solution.
[Related to: Gr. 9/10 Science – Chemistry unit]
(C-4) Dying of the fire dragon -- Methane gas + Soap
bobbles
Materials: Methane gas (Bunsen burner gas), soap
bubbles solution
[Related to: Gr. 9/10 Science – Chemistry unit]
Extra Safety Note: Wet your hands prior to handling the soap bubbles before burning
(C-5) Sparkling finger -- Lighting up Bunsen burner using
index finger
Materials: Van de graaff generator, short plastic stool (or
inverted recycling bin), Bunsen burner
[Related to: Gr. 9/10 Science – Chemistry unit, Gr. 11/12
Physics – Electricity unit]
THE END
Tips: Try the demonstrations/discrepant
events before showing students!
benjamin.law@yrdsb.edu.on.ca